Related Applications
This application is filed concurrently with "Improved Video Processing Using Scan-Line Video Processors", and "Sharpness Control for Digital Displays,".
Field of the Invention
This invention relates to display systems, more particularly to display systems that use digital processing of the video signals.
Background of the Invention
The current majority of display systems involve cathode ray tube (CRT) displays which have scanning guns that "spray" electrons onto the phosphors on the back side of the display screen. Due to the nature of the scanning guns, broadcast video signals are sent in an interlaced format. Each frame of data is divided into two fields, one containing the odd-numbered lines of the frame, the other containing the even-numbered lines.
Certain technologies are moving to the forefront of the display market, however, that cannot use this type of format. One example is spatial light modulators, which normally consist of an array of individually selectable elements over addressing circuitry that is addressed to make the selection. The addressing circuitry of these modulators is typically organized in rows and columns, making the selection of all of the odd-numbered lines or the even-numbered lines awkward, slow and costly.
Methods have been developed to alter the format of this data to a progressively scanned format, where the entire frame of data is formed. Often times this formation occurs by interpolating the missing field using previous fields to estimate the pixel values of the missing fields. This interpolation process can be expensive and computationally demanding, driving up the system performance requirements and the cost.
Another adaptation that must be made is the ability of the system to display different formats of incoming data. Typically, in CRT systems the incoming format remained an analog input and the guns just adjusted to the new dimensions. With the individual elements in the arrays, there is sometimes a one-to-one correspondence between the pixels on the image and the elements. For example, a system with 640 pixels per line and 480 lines would require a device that had 640 elements per line and 480 lines of elements, not including any scaling possibilities.
The incoming data is typically digitized at a rate equal to the pixels per line dimension in these types of systems. The 640 pixels per line would be digitized at 640 samples per line. The processor, therefore, must be able to adjust not only for displaying more than one format on a fixed number of elements in the array, but to have a sampling rate that is compatible with any given format.
One new advance in the video processing area is the scan-line video processor. These processors have several advantages that allow the solutions to the above problems. However, the first versions of these processors had an extremely limited instruction space, requiring the use of several processors in a display system. The newer versions of these processors have more instruction space, and are priced competitively when compared with the previous version.
Therefore, a system using the newer versions of scan-line video processors is needed that uses the fewest possible processors while still allowing the full functionality mentioned above.